Extract rule: template-no-yield-only

[NullVoxPopuli]

Split from #2371.

[NullVoxPopuli-ai-agent]

Review: template-no-yield-only (PR #2596)

Comparison with ember-template-lint no-yield-only.js

General correctness:

1. Logic difference in what counts as "empty": The original's isEmptyNode considers MustacheCommentStatement, CommentStatement, and whitespace-only TextNode as empty. The PR's IGNORABLE_TYPES set only includes GlimmerTextNode and GlimmerMustacheCommentStatement, but the isMeaningfulContent function also handles GlimmerTextNode specially (checking if trimmed content is non-empty). Missing: GlimmerCommentStatement (HTML comments like <!-- ... -->) is not in IGNORABLE_TYPES, so an HTML comment + yield would NOT trigger the rule, whereas in the original it would. Consider adding 'GlimmerCommentStatement' to IGNORABLE_TYPES.

2. isYieldOnly vs isBareYield: The original checks node.params.length === 0 but does not check node.hash. The PR additionally checks !node.hash || !node.hash.pairs || node.hash.pairs.length === 0. This is actually stricter — {{yield to="inverse"}} has zero params but has hash pairs, and the original would consider it a "yield only" while the PR would not. Looking at the test cases, {{yield (hash someProp=someValue)}} is valid in both, which has params. The PR's extra hash check seems correct/desirable since {{yield to="inverse"}} is not really a "bare yield".

   Wait — actually re-reading the original: it checks node.params.length === 0 which would be true for {{yield to="inverse"}} (hash pairs are not params). So the original would flag {{yield to="inverse"}} as yield-only, which seems like a bug in the original. The PR's stricter check that also requires no hash pairs is actually an improvement.

3. GlimmerTemplate visitor: The PR handles both gjs (where body[0] is a GlimmerElementNode for <template>) and hbs (where body directly contains nodes). This is a reasonable approach though the heuristic of checking firstChild.type === 'GlimmerElementNode' could theoretically be fragile if the parser representation changes. Consider adding a comment explaining this distinction.

Scope analysis (gjs/gts):

The rule checks node.path.original === 'yield'. yield is a Glimmer keyword and cannot be shadowed. No scope analysis needed.

Overall: Good migration with one minor gap — consider adding GlimmerCommentStatement to IGNORABLE_TYPES to match the original's treatment of HTML comments as empty content.

🤖 Automated review comparing with ember-template-lint source